Firearm construction



y 2, 1946- F. SAMPSON EI'AL I 2,403,306

FIREARM CONSTRUCTION Filed May 1, 1944 2 Sheets-Sheet l ficw. 5H2 WU W i F m July 2, 1946.

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aa/MUMM f I Patented July 2, 1946 FIREARM CONSTRUCTION Frederick W. Sampson, Dayton, Ohio, and George J. Hyde, Brooklyn, N. Y., asslgnors to General Motors Corporation, a corporation of Delaware Application May 1, 1944, Serial No. 533,569

Claims.

This invention relates to an improved bolt guiding construction for a firearm of the type commonly referred to as a submachine gun or machine pistol.

It is the principal object of this invention to produce a firearm in which the bolt is guided in its reciprocation with accuracy and certainty and one which is not liable to stoppages as a result of exposure to dust, mud, or other foreign elements.

It is a further object of this invention to produce a bolt mechanism assembly for a firearm which may be removed as a unit from the fire-'- arm for inspection and cleaning without danger of loss or displacement of springs or other parts.

An additional object is the provision of a bolt guiding construction which requires in its production a minimum of machine work without sacrificing in accuracy and reliability of functioning.

The exact nature of our invention as well as other objects and advantages thereof will be clearly apparent from a study of the following specification referring to the drawings annexed hereto in which:

Fig. l is a longitudinal vertical sectional view through a firearm embodying this invention;

Figs. 2, 3 and 4 are cross sectional views on the lines 2-2, 3-3 and 6-4, respectively, of Fig. 1;

Fig. 5 is a longitudinal, sectional view taken substantially along the plane of the line 5-5 of Fig. 1;

Fig. 6 is a pictorial view of the bolt mechanism assembly removed from the receiver.

Referring to the drawings by characters of reference it will be seen that the firearm shown therein is of the same general type as that shown in our copending applications for U. S. Letters Patent, bearing Serial Nos. 533,566; 533,567; 533,568; and 533,570, filed May 1, 1944, and in which the subject matter disclosed but not.

claimed in this application is claimed, and comprises a receiver I to which a barrel sleeve 4 has been welded or otherwise secured. A barrel 6 is threadedly engaged with the barrel sleeve 4 through the medium of the externally threaded barrel bushing 8.

The receiver. serves as a housing for the bolt assembly, shown separately in Fig. 6, which comprises a breech bolt i0 formed with an integral firing pin II and provided with a spring extractor finger l2 received in a longitudinal bore in the bolt and retained therein by a transverse pin it. A pair of spaced holes H penetrate the bolt longitudinally and are each in substantially parallel relation to-the axis of :the bolt. A pair of spaced parallel bolt guide rods l5 are fixed in" the.

guide rod retaining plate I8. Surrounding the guide rods and confined thereon between the re taining plate It and rearwardly facing surfaces Ma on the bolt are a pair of drivingsprings IT. The guide rods extend forwardly through the -bolt guide holes l4 and pass through holes in the guide rod locating plate l8 which engages forwardly facing shoulders i5a on each of the guide rods. Grooves I9 inthe ends or each of the guide rods-forward of the locating plate are engaged by a guide rod retaining clip 20, shown clearly in Figs. 3 and 6.

When the bolt mechanism assembly is inserted into the front end of the receiver lateral projections or locating lugs 2! on the locating plate It are engaged in grooves 22 in the barrel sleeve 4 and the rear ends of the guide rods l5= are received in the holes 23 formed in the rear wall of the receiver. When the barrel bushing '6 is screwed into the receiver in front of the bolt assembly the rear face of the bushing engages the front face of the guide rod locating plate and .forces the plate, guide rods, and retaining plate back into tight engagement with the rear wall of the receiver. The rear end of the barrel 5 extends through the central aperture I 8a in the locating plate in position to receive in the chamber 5a cartridges fed from the magazine 33. It

will be noted that when the parts are secured in this manner the ends of the guide rods and" the retaining clip are engaged in'an annular space defined by the barrel bushing, the barrel and the locating plate, and that it is impossible for the clip to become loosened. or deranged.

It will be readily apparent that by this means the entire bolt and bolt guiding mechanism has been integrated into a compact and convenient subassembly which may be removed from the receiver as a. unit and which normally need not be further disassembled for cleaning or inspection. When occasion does arise calling for further disassembly or replacement of parts the retaining clip may be readily removed and the locating plate and bolt allowed to slip 011 of the ide rods.

Althoughno detailed description of the lower housing has been includedin this application it is believed that it will be evident that the lower housing 44 carrying the ejector I2 and cooking mechanism must be removed before removal of the bolt mechanism can be eflectuated. Removal of the lower housing 'is simply achieved by deforming the resilient trigger guard 49 out of engagement with the-holein the grip and with- 3 drawing the arched end of the guard from the matching holes 41 and 48, respectively, in the housing and receiver. These features are fully described in our copending application above referred to.

It will be noted that the guide,rods furnish complete support and control of the movement of the bolt independently of the walls of the receiver during all phasesof bolt travel. This permits the receiver to be formed by stamping or other production methods and without necessitating close tolerances and difiicult machining operations on the inner wall of the receiver.. At thesame time the bolt is guided with a, high degree of accuracy, smoother operation is attained, and uniformity of drive spring loading is readily achieved.

This sort of construction presents a minimum of operating and maintenance problems under diflicult service conditions since the contacting area between the bolt and its guiding means is greatly reduced as compared to conventional constructions and the bearing area is situated in a well protected position. The spacing which is maintained between the bolt and the wall of the receiver insures that if foreign material should get into the receiver it may not readily jam the mechanism by wedging in a restricted space.

We claim:

1. A firearm comprising a receiver having a substantially closed rear end, locating holes in the rear end, bolt guide rods received in the locating holes, a bolt-slidably mounted on the rods and within the receiver, grooves in the inner surface of the forward end of the receiver, a locating plate having means engaging the grooves and the guide rods, and a barrel bushing engaging the receiver and confining the locating plate and the guiderods.

2. A firearm comprising a receiver, bolt guide rods in the receiver, a bolt slidable on the rods, a centrally apertured guide rod locating plate on the forward end of the rods and engaging the receiver, spring clip means on the rods to secure the plate thereto, a barrel passing through the central aperture, and a barrel bushing on the barrel engaged with the receiver and with the forward face of the locating plate.

3. A firearm comprising a receiver, a bolt guide assembly in the receiver having a pair of elongated parallel guide rods, a centrally apertured locating plate engaging the receiver and having holes through which the guide rods may pass, opposed grooves in the guide rods, a spring clip exerting resilient outward pressure on the guide rods and engaged in the grooves whereby the plate is secured on the rods, and a barrel assemgly having a portion passing through the central aperture in the locating plate whereby the spring clip is prevented from dislodgment.

4. For use in a firearm a bolt mechanism comprising, a plurality of substantially parallel guide rods having annular grooves adjacent to their forward ends, a retaining plate attached to the rear ends of said guide rods, a bolt including means forming a plurality of longitudinally extending holes therein in which said guide rods are slidably received, driving springs surrounding said rods and operatively engaged for compression between said plate and said bolt, a locating member including a plurality of outwardly extending locating lugs thereon and a plurality of apertures therein receiving the forward ends of said rods, and a resilient retaining clip engaging said grooves forward of said member.

5. For use in a firearm a bolt mechanism comprising, a plurality of guide rods having locking means adjacent their front ends, a retaining plate attached to the rear ends of said rods, a bolt including means forming a plurality of longitudinally extending holes therein in which said rods are slidably received, driving springs surrounding said rods between said plate and said bolt, a locating member in engagement with the forward ends of said rods, and resilient means engaged with said locking means for releasably retaining said rods and said member in engagement.

FREDERICK W. SAIWPSON. GEORGE J. HYDE. 

